Freeze() and Thaw()

In the main frame of one of my applications, I have this sequence:

     self.Freeze()
     building-and-layout-of-the-initial-display
     self.Thaw()

I thought that, when self.Thaw() is executed, my PC screen would instantly fill with the initial display.

What I see instead is some of the panel-building and layout happening before my eyes. A seeming "premature thaw" or "premature curtain-raising" of sorts. Time from startup to completed display is only about a second, but the look, to me, is unprofessional.

Any idea what might be causing this behavior? Any idea how I might zero in on this visual annoyance?

Bob